The present invention is related to cooling of airfoils for gas turbine engines and, more particularly, to baffle inserts for impingement cooling of airfoil vanes. Gas turbine engines operate by passing a volume of high energy gases through a series of compressors and turbines in order to produce rotational shaft power. The shaft power is used to turn a turbine for driving a compressor to provide air to a combustion process to generate the high energy gases. Additionally, the shaft power is used to power a secondary turbine to, for example, drive a generator for producing electricity, or to produce high momentum gases for producing thrust. Each compressor and turbine comprises a plurality of stages of vanes and blades, each having an airfoil, with the rotating blades pushing air past the stationary vanes. In general, stators redirect the trajectory of the air coming off the rotors for flow into the next stage. In the compressor, stators convert kinetic energy of moving air into pressure, while, in the turbine, stators accelerate pressurized air to extract kinetic energy.
In order to produce gases having sufficient energy to drive both the compressor and the secondary turbine, it is necessary to compress the air to elevated temperatures and to combust the air, which again increases the temperature. Thus, the vanes and blades are subjected to extremely high temperatures, often times exceeding the melting point of the alloys used to make the airfoils. In particular, the leading edge of an airfoil, which impinges most directly with the heated gases, is heated to the highest temperature along the airfoil. The airfoils are maintained at temperatures below their melting point by, among other things, cooling the airfoils with a supply of relatively cooler air that is typically siphoned from a compressor. The cooling air is directed into the blade or vane to provide cooling of the airfoil through various modes including impingement cooling. Specifically, the cooling air is passed into an interior of the airfoil to remove heat from the alloy. The cooling air is subsequently discharged through cooling holes in the airfoil to pass over the outer surface of the airfoil to prevent the hot gases from contacting the vane or blade. In other configurations, the cooling air is typically directed into a baffle disposed within a vane interior and having a plurality cooling holes. Cooling air from the cooling holes impinges on an interior surface of the vane before exiting the vane at a trailing edge discharge slot.
Due to the extremely thin nature of the baffle, it is difficult to control the cooling air as it leaves the baffle. Various baffle designs have been developed to better distribute cooling air along the interior surfaces of the vane. Many previous baffle designs require extensive fabricating, shaping and assembly steps, which increase manufacturing time and expense. There is, therefore, a need for a simpler baffle design that is easy to produce and cost effective.